This study involves a multifaceted approach to the evaluation of knee ligamentous injuries generated in sports. In our area, most such injuries are produced by ski accidents, thus we are monitoring all ski injuries generated at Glen Ellen ski area and are specifically studying the mechanism of production of knee injury. The bindings of injured skiers are evaluated in a very sophisticated fashion to determine the relationship of binding dysfunction to knee ligamentous injury production. The medial collateral ligament of human bone-ligament-bone specimens are being disrupted in vivo at strain rates consistent with those occurring in real trauma. Cyclic stress to failure will be done on the knee ligaments of rats. The effect of athletic stress on the stiffness of human knee ligaments will be documented. Mechanical impedance will continue to be utilized to evaluate in vivo the effects of various ligamentous disruptions in human knees, as well as to determine if physical conditioning has any effect on ligamentous stiffness or strength.